1. Field of the Invention
This invention relates to a method of evaluating the adhesiveness of a member. More particularly, the present invention relates to an adhesiveness evaluation method that can suitably be used for evaluating the adhesiveness of a thin film in a micro-region.
2. Related Background Art
Known adhesiveness evaluation methods (e.g., a method of evaluating the adhesiveness of a thin film relative to a substrate on which the film is formed, for example) include the pulling/peeling test, the scratching test and the pressure mark test.
With the cross-cut adhesion test, which is a type of pulling/peeling test, the thin film formed on a substrate is cut to produce a checker pattern and a sticky tape is applied to the surface of the thin film. Subsequently, the sticky tape is peeled off and the number of small squares of thin film that are peeled off from the substrate with the sticky tape is counted to evaluate the adhesiveness of the thin film.
With the scratch test, a very hard needle (stylus) is vertically pressed against the thin film formed on a substrate and then driven to move in a horizontal direction with a load being applied to the stylus in order to scratch the thin film. Then, the load that produces a scratch on the thin film is observed to evaluate the adhesiveness of the thin film.
With the pressure mark test, a load is applied to the surface of the thin film formed on a substrate by means of a micro Vickers hardness meter and then gradually raised so as to evaluate the adhesiveness of the thin film by observing the peeled condition of the thin film produced around the pressure mark on the thin film.
Japanese Patent Application Laid-Open No. 2002-005817 describes a method for evaluating the adhesiveness of a thin film applied and adhered to a substrate by winding a specimen consisting of a substrate and an applied thin film around a part of the test roller having a predetermined diameter and forcing it to bend in order to see the peeled condition of the applied film and evaluate the adhesiveness of the applied film relative to the substrate.
As described above, known adhesiveness evaluation methods have been developed on an assumption of using a macro-size specimen as an object of measurement.
Meanwhile, with the advancement of film-forming techniques and micro-machining techniques in recent years, there has arisen a demand for evaluating the physical properties of a micro-part of a specific spot of a small specimen, which may typically be any of various devices or micro-machines.
The physical properties of a specimen to be evaluated typically include the morphology, the crystallinity, the defects, the impurities and the component elements of the specimen. In certain cases, the adhesiveness of the specimen is also one of the basic parameters to be evaluated.
For instance, the durability and the reliability of a device comprising a thin film showing a poor adhesiveness may be low. In other words, there are many products whose quality is improved when the adhesiveness of the products is improved.
However, a micro-size specimen, which may be any of various devices or micro-machines, more often than not has a complex structure within a micro-part thereof. It means that the adhesiveness can vary within the micro-part. Hence, a specific spot of a micro-part of the specimen may have to be selected and evaluated for adhesiveness.
On the other hand, known adhesiveness evaluation methods have been developed on an assumption of using a macro-size specimen as the object of measurement, as pointed out above. Hence, it is not possible to select a specific spot (of the order of magnitude of nanometers to micrometers) of a micro-part and evaluate the adhesiveness of the spot using any of the known adhesiveness evaluation methods.
Attempts have been made to prepare a sham specimen (for example, a plain thin film formed on a substrate) and evaluate the adhesiveness of the sham specimen by means of a known adhesiveness evaluation method in order to replace an adhesiveness evaluation test of a specific spot of a micro-part of a comparable real specimen (which may be any of various devices or micro-machines). However, in many cases, an adhesiveness evaluation test using such a sham specimen is not equivalent to an adhesiveness evaluation test conducted on a specific spot of a micro-part of a real specimen because the sham specimen and the real specimen do not necessarily represent the same condition.